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Title: Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics

Abstract

Here, to compete with existing and more mature solar cell technologies such as crystalline Si, thin-film photovoltaics require optimization of every aspect in the device heterostructure to reach maximum efficiencies and cost effectiveness. For absorbers like CdTe, Cu(In,Ga)Se2 (CIGSe), and Cu2ZnSn(S,Se)4 (CZTSSe), improving the n-type buffer layer partner beyond conventional CdS is one avenue that can reduce photocurrent losses and improve overall performance. Here, we use first-principles calculations based on hybrid functionals to explore alloys spanning the Cd-, Zn-, O-, and S-containing phase space to identify compositions that may be superior to common buffers like pure CdS or Zn(O,S). We address issues highly correlated with device performance such as lattice-matching for improved buffer-absorber epitaxy and interface quality, dopability, the band gap for reduced absorption losses in the buffer, and the conduction-band offsets shown to facilitate improved charge separation from photoexcited carriers. We supplement our analysis with device-level simulations as parameterized from our calculations and real devices to assess our conclusions of low-Zn and O content buffers showing improved performance with respect to CdS buffers.

Authors:
 [1];  [1];  [2];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1418936
Alternate Identifier(s):
OSTI ID: 1371613
Report Number(s):
LLNL-JRNL-726081
Journal ID: ISSN 2475-9953; PRMHAR; TRN: US1801316
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 1; Journal Issue: 2; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE

Citation Formats

Varley, J. B., Lordi, V., He, X., and Rockett, A. Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics. United States: N. p., 2017. Web. doi:10.1103/PhysRevMaterials.1.025403.
Varley, J. B., Lordi, V., He, X., & Rockett, A. Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics. United States. doi:10.1103/PhysRevMaterials.1.025403.
Varley, J. B., Lordi, V., He, X., and Rockett, A. Mon . "Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics". United States. doi:10.1103/PhysRevMaterials.1.025403. https://www.osti.gov/servlets/purl/1418936.
@article{osti_1418936,
title = {Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics},
author = {Varley, J. B. and Lordi, V. and He, X. and Rockett, A.},
abstractNote = {Here, to compete with existing and more mature solar cell technologies such as crystalline Si, thin-film photovoltaics require optimization of every aspect in the device heterostructure to reach maximum efficiencies and cost effectiveness. For absorbers like CdTe, Cu(In,Ga)Se2 (CIGSe), and Cu2ZnSn(S,Se)4 (CZTSSe), improving the n-type buffer layer partner beyond conventional CdS is one avenue that can reduce photocurrent losses and improve overall performance. Here, we use first-principles calculations based on hybrid functionals to explore alloys spanning the Cd-, Zn-, O-, and S-containing phase space to identify compositions that may be superior to common buffers like pure CdS or Zn(O,S). We address issues highly correlated with device performance such as lattice-matching for improved buffer-absorber epitaxy and interface quality, dopability, the band gap for reduced absorption losses in the buffer, and the conduction-band offsets shown to facilitate improved charge separation from photoexcited carriers. We supplement our analysis with device-level simulations as parameterized from our calculations and real devices to assess our conclusions of low-Zn and O content buffers showing improved performance with respect to CdS buffers.},
doi = {10.1103/PhysRevMaterials.1.025403},
journal = {Physical Review Materials},
number = 2,
volume = 1,
place = {United States},
year = {2017},
month = {7}
}

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